Critical to the effective regenerative regulation of a beverage's temperature, through the use of a melting phase-change material is the speed of the regulation. The speed of regulation is determined in part by the ease with which heat may flow between the beverage and the phase change material. If the speed at which the beverage's heat is transferred to the phase-change material is slow, much of this heat will be irretrievably lost to the air, through the beverage's upper surface. As the beverage cools further, if the heat stored in the phase-change material cannot be quickly released, the temperature of the beverage will not be properly maintained.
A slow speed of temperature regulation will be unacceptable to a consumer who desires the contained beverage be quickly reduced to a drinkable temperature and maintained at that temperature for the longest possible time.
The prior art has addressed this problem of heat transfer, in a number of ways. H. G. Zimmerman, et al., U.S. Pat. No. 2,876,634, teaches the use of metallic fins integral to the inner wall of the cup and directed into the wax. E. A. Rollor, Jr, U.S. Pat. No. 3,463,140, shows the use of non-integral fins of corrugated metal foil dispersed through the volume of the wax. This patent also discloses a method for brazing these foil fins to the wall of the cup to ensure good thermal contact. J. W. Ryan, et al., U.S. Pat. No. 3,603,106, discloses a means for temporarily increasing the thermal conductivity of the wax by mixing the wax with fine particles of aluminum. All of these techniques serve to reduce the effective thermal resistance within the wax itself.